Editing Zoonosis (section)

===Secondary Transmission===
Zoonotic diseases contribute significantly to the burdened public health system as vulnerable groups such the elderly, children, childbearing women and immune-compromised individuals are at risk.{{citation needed|date=August 2024}} According to the [[World Health Organization (WHO)]], any disease or infection that is primarily ‘naturally’ transmissible from vertebrate animals to humans or from humans to animals is classified as a zoonosis.<ref name=":0">{{Cite journal |last1=Rahman |first1=Md Tanvir |last2=Sobur |first2=Md Abdus |last3=Islam |first3=Md Saiful |last4=Ievy |first4=Samina |last5=Hossain |first5=Md Jannat |last6=El Zowalaty |first6=Mohamed E. |last7=Rahman |first7=AMM Taufiquer |last8=Ashour |first8=Hossam M. |date=September 2020 |title=Zoonotic Diseases: Etiology, Impact, and Control |journal=Microorganisms |language=en |volume=8 |issue=9 |pages=1405 |doi=10.3390/microorganisms8091405 |doi-access=free |issn=2076-2607 |pmc=7563794 |pmid=32932606}}</ref> Factors such as climate change, urbanization, animal migration and trade, travel and tourism, vector biology, anthropogenic factors, and natural factors have greatly influenced the emergence, re-emergence, distribution, and patterns of zoonoses.<ref name=":0" />

Zoonotic diseases generally refer to diseases of animal origin in which direct or vector mediated animal-to-human transmission is the usual source of human infection. Animal populations are the principal reservoir of the pathogen and horizontal infection in humans is rare. A few examples in this category include lyssavirus infections, Lyme borreliosis, plague, tularemia, [[leptospirosis]], ehrlichiosis, Nipah virus, West Nile virus (WNV) and hantavirus infections.<ref name=":1">{{Cite journal |last1=SCHLUNDT |first1=J. |last2=TOYOFUKU |first2=H. |last3=FISHER |first3=J.R. |last4=ARTOIS |first4=M. |last5=MORNER |first5=T. |last6=TATE |first6=C.M. |date=2004-08-01 |title=The role of wildlife in emerging and re-emerging zoonoses |url=http://dx.doi.org/10.20506/rst.23.2.1498 |journal=Revue Scientifique et Technique de l'OIE |volume=23 |issue=2 |pages=485–496 |doi=10.20506/rst.23.2.1498 |issn=0253-1933}}</ref> Secondary transmission encompasses a category of diseases of animal origin in which the actual transmission to humans is a rare event but, once it has occurred, human-to-human transmission maintains the infection cycle for some period of time. Some examples include [[HIV|human immunodeficiency virus (HIV)]]/acquired immune deficiency syndrome (AIDS), certain influenza A strains, [[Ebola]] virus and severe acute respiratory syndrome (SARS).<ref name=":1" />

One example is Ebola which is spread by direct transmission to humans from handling [[bushmeat]] (wild animals hunted for food) and contact with infected bats or close contact with infected animals, including chimpanzees, fruit bats, and forest antelope. Secondary transmission also occurs from [[Human-to-human transmission|human to human]] by direct contact with blood, bodily fluids, or skin of patients with or who died of Ebola virus disease.<ref>{{Cite journal |last1=Rewar |first1=Suresh |last2=Mirdha |first2=Dashrath |date=2015-05-08 |title=Transmission of Ebola Virus Disease: An Overview |journal=Annals of Global Health |language=en-US |volume=80 |issue=6 |pages=444–451 |doi=10.1016/j.aogh.2015.02.005 |pmid=25960093 |issn=2214-9996|doi-access=free }}</ref> Some examples of pathogens with this pattern of secondary transmission are human immunodeficiency virus/acquired immune deficiency syndrome, influenza A, Ebola virus and severe acute respiratory syndrome. Recent infections of these [[Emerging infectious disease|emerging]] and re-emerging zoonotic infections have occurred as a results of many ecological and sociological changes globally.<ref name=":1" />